A boy and girl were playing together. The boy had a collection of marbles and girl had some sweets with her. Boy asked girl to give him sweet in exchange of his marbles. Girl agreed. When it came to exchange boy got greedy and kept the biggest and most beautiful marble with himself and gave rest to her in exchange to sweets. So girl gave him all the sweets in exchange of marbles as agreed. Same night boy when boy went to sleep he kept on thinking about the deal because he kept wondering if girl had same as boy. If girl had kept some sweets with her as boy kept marble with himself. It's a small story but makes us think about our relationships. 
If we ourselves don't give hundred percent in a relation then we will always have doubt and kept on wondering what if partner is doing same with you. So always be true to yourself and partner. 